1. Field of Invention
The present invention generally relates to a light source module and a display. More particularly, the present invention generally relates to a backlight module and a liquid crystal display.
2. Description of Related Art
The liquid crystal display (LCD) mainly consists of a liquid crystal panel and a backlight module. Since the liquid crystals in the liquid crystal panel are unable to emit light spontaneously, the backlight module is used as the surface light source to provide light for display.
The backlight module can be categorized as the edge-light type and the straight-down type. For the edge-light type backlight module, a light guide plate is used to disperse the light from the point light source and thus converts it into a plane light source for the liquid crystal panel. However, the straight-down type backlight module requires no light guide plate and provides the plane light source directly. Hence, when higher luminance is required for the liquid crystal display, the straight-down type backlight module is generally applied. The light source of the straight-down type backlight module commonly consists of a plurality of cold cathode fluorescent lamps (CCFL) arranged in parallel.
FIG. 1 is the cross-sectional view of the prior art straight-down type backlight module. As shown in FIG. 1, a plurality of cold cathode fluorescent lamps (CCFL) 120 is arranged in parallel in the light box 110 and the diffuser plate 130 and optical sheets 140 including reflection sheet(s) or prism sheet(s) are installed at the opening 112 of the light box 110. The light emitting from the lamps 120 is diffused or refracted by the diffuser plate 130 and then emits from the diffuser plate 130 as the plane light source.
The lamps 120 in the prior art structure are arranged in parallel to the diffuser plate 130 and to the bottom surface 114 of the light box 110. However, current leakage often occurs due to the small distance between the lamps 120 and the bottom surface 114 of the light box 110. Therefore, the high voltage terminal and the low voltage terminal of the lamp 120 have different values of currents, resulting in brightness variation. In general, upon the influence of current leakage, the high voltage terminal of the lamp 120 is brighter than the low voltage terminal. In addition, because of the arrangement of the lamps in the backlight module, the regions near the outermost lamps are dimmer. Accordingly, the prior art is unable to provide the backlight module suitable as the uniform plane light source, and the display quality of the liquid crystal display can be compromised.